Abstract: PTEN exerts tumor suppressor role through inhibiting PI3K/AKT signaling. DJ-1 plays an oncogenic role through negatively regulation of PTEN expression. Curcumin (Cur) is a phenolic compound extracted from a variety of plant roots, with multiple anti-tumor pharmacological effects. This study aims to investigate whether Cur plays a role in the regulation of DJ-1-PENT/PI3K/AKT signaling as well as the proliferation and apoptosis of hepatocellular carcinoma cells. Normal human hepatocyte HL-7702 and hepatocellular carcinoma cell lines SMMC-7721 and HepG2 were cultured followed by analysis of the expression of DJ-1 and PTEN. SMMC-7721 and HepG2 cells were treated with different concentrations of Cur (0, 5, 10 μM) followed by measuring cell proliferation by CCK-8, caspase-3 activity as well as DJ-1 expression by western blot. In addition, SMMC-7721 or HepG2 cells were divided into two groups: Cur+pcDNA3.1-Blank and Cur+pcDNA3.1-DJ-1 for analysis of the expression of DJ-1, PTEN and p-AKT, cell apoptosis and proliferation. Compared with HL-7702, SMMC-7721 and HepG2 cells displayed significantly higher DJ-1 expression and lower PTEN expression. Cur treatment significantly inhibited proliferation of SMMC-7721 and HepG2 cells, increased caspase-3 activity and downregulated DJ-1 expression. Transfection of pcDNA3.1-DJ-1 significantly increased DJ-1 and p-AKT expression, promoted cell proliferation, but decreased PTEN expression and cell apoptosis. In conclusion, Cur inhibits proliferation of hepatocellular carcinoma cells and PTEN/PI3K/AKT signaling pathway via the reduction of DJ-1 expression, which provides new insights to the anticancer effects of curcumin in hepatocellular carcinoma.
